1. Field of the Invention
The present invention relates to a circuit device that has an element and a method for manufacturing the same.
2. Description of Related Art
A vehicle is provided with various electronic equipments. For example, an air bag system is one of the electronic equipments. In the air bag system, a sensor mounted on the vehicle outputs a signal to an ECU, and the ECU determines collision based on the received signal. When the collision is determined, an air bag mounted on the vehicle is inflated.
The ECU mounted on the vehicle includes a case and a circuit board that is provided with a chip. The circuit board is received within the case of the ECU in order to achieve resistance to climatic conditions and the like. The ECU is connected with an exterior device through a communication connector that is exposed to the exterior from the surface of the case. The communication connector is assembled to the circuit board and is fixed to the case.
There is provided a receiving part that is cut out at a side wall part of the case, which receiving part receives therein the connector. The connector is fitted into the receiving part such that the connector is fixed to the case. In the above, the receiving part is defined by a peripheral edge part of the case, and the peripheral edge part is provided between a pair of projections of the connector. The connector is press-fitted into the peripheral edge part in a state, where the peripheral edge part is positioned between the projections. Also, the peripheral edge part has at least one surface that is angled to form a tapered surface such that the tapered surface is brought into contact with the projection. During the press-fitting of the connector, the tapered surface leads the connector into the case, and the projection of the connector is brought into press-contact with the tapered surface of the peripheral edge part at a predetermined position relative to the peripheral edge part such that the connector is fixed to the case.
In the above, the connector is made of a resin, and the case and the peripheral edge part are made of a metal that is harder than the resin. Thus, when the connector is press-fitted, a contact portion of the projection, which contacts the tapered surface, elastically deforms, and thereby the projection is brought into press-contact with the tapered surface.
Recently, a press-fit terminal is widely used for connection between the connector and the circuit board. Typically, the press-fit terminal includes a column end portion, a contact portion, and a tapered portion. The contact portion has a diameter wider than a diameter of the end portion, and the tapered portion connects the end portion and the contact portion. An electrical conductor is formed at an inner peripheral surface of a through hole that opens at the circuit board. The press-fit terminal is electrically conductive with the electrical conductor of the through hole of the circuit board through the contact portion, and fixes the connector (element) that is connected with the terminal.
The contact portion of the press-fit terminal has an outer diameter greater than an inner diameter of the through hole that opens at the circuit board, and the press-fit terminal is assembled by inserting the end portion into the through hole. As a result, it is difficult to accurately assemble the press-fit terminal at a position in a direction along the depth of the through hole. In other words, accuracy in positioning of the connector connected with the press-fit terminal relative to the circuit board is insufficiently achieved. When the accuracy in the assembly of the connector deteriorates, accuracy of the position of the connector relative to the peripheral edge part of the case varies in the process of assembling the circuit board at a predetermined position within the case. In other words, the thickness of, the tapered surface of the peripheral edge part at a position, at which the projection of the connector is located, varies. When the thickness of the tapered surface is small, the press-contact force exerted between the projection and the tapered surface is small. In contrast, as the thickness of the tapered surface becomes large, the press-contact force becomes large accordingly, and thereby large force is required during the assembly. When the large force is required, the cost required in the assembly of the circuit board to the case also increases.
As above, when the press-fit terminal is employed for assembly of the connector to the circuit board, the force required for the assembly of the connector may vary, and thereby the cost required for the assembly of the circuit board to the case may increase disadvantageously.